High-speed optical switching based on diffusive conduction in an optical waveguide with...
-
date post
21-Dec-2015 -
Category
Documents
-
view
214 -
download
0
Transcript of High-speed optical switching based on diffusive conduction in an optical waveguide with...
High-speed optical switching based on diffusive conduction in an opticalwaveguide with surface-normal optical control
V. A. Sabnis, H. V. Demir, M. B. Yairi, J. S. Harris, Jr., and D. A. B. Miller
Edward L. Ginzton Laboratory and Solid State and Photonics Laboratory,
Stanford University, 450 Via Palou, Stanford, California 94305
Journal of Applied Physics, Volume 95, 2258 (2004)
Presenter: F. Hakan Köklü
Outline Introduction Concept of diffusive conduction Device concept Theoretical results Experimental results Conclusions
Introduction All-optical information transfer schemes vs.
conventional optical-electronic-optical conversion A single p-i-n diode containing multiple quantum
wells performing wavelength conversion and optical regeneration at mW power levels
Two-dimensional scalability and integration with electronics
Quantum confined Stark effect Diffusive conduction High extinction ratio
Concept of Diffusive Conduction
2
20
, 0 exp/ 2M
rV r t V
w
2
, exp4M
rV r t V
t D t
2
0 1
42
w
D
dVD V
dt 2ÑDiffusion Equation:
(Ohm’s Law, Kirchoff’s Laws, Q=CV)
Initial Condition:
Solution:
RSQ = Resistance per squareCA = Capacitance per unit area
DR CSQ A
1
Device Concept Quantum confined
Stark effect Field screening Modulating the signal
output by control input Non-inverting optical
switching Wavelength
conversion Local capacitor
Device Concept
Diffusion equation in one dimension .
Solution:
where
for a switch having the local capacitor at the edge of the waveguide.
2
2
dx
VdD
dt
dV
1
2 )exp(12
)sin(4),(
mm
m tDm
xVtxV
L
mm 2
)12(
Device Concept
Theoretical Results
A simulation model in conjunction with empirically measured quantum well data is established.
Modulation bandwidths of tens of GHz.
Theoretical Results
Simulation of 10 Gb/s nonreturn-to-zero operation with a 2μm wide, 250μm long center bias point device
Rl = 16 Ohm/μm
Cl = 0.23 fF/μm
λcontrol = 822nm
λsignal = 864nm >10 dB signal extinction
ratio
Experimental Results
A 2μm wide, 300μm long device for single transverse mode operation for wavelengths longer than 860nm
Waveguide is designed to be a surface-illuminated photodetector between 814nm-833nm.
Quantum wells are engineered to have an absorption edge at 850nm.
Rl = 16 Ohm/μm, Cl = 0.23 fF/μm
λcontrol = 822nm, λsignal = 868nm A continuous-wave Ti-sapphire for signal beam and a
diode laser for control beam were used.
Experimental Results
Reverse biases greater than 5 V results in significant increase in absorption.
7.7 dB signal transmission change is observed with an incident control beam power of 7.8 mW and a reverse bias of 7 V.
Experimental Results At 2.5 GHz, wavelength-
converting optical modulation is demonstrated.
Distortions at the output signal beam due to mechanical instability
The ability to electrically enable or disable the device using bias voltage.
Conclusions
A wavelength-converting, surface-normal optically controlled, waveguide switch based on diffusive electrical conduction is demonstrated.
Possibility of tens of GHz optical switching with mW-level optical switching powers
Two dimensional scalability for high-density switching